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Effect of High Magnetic Field on Phase Transformation and Carbide Precipitation in Fe-0.28%C-3.0%Mo Alloy

Author: ZhouZhenNi
Tutor: WuKaiMing
School: Wuhan University of Science and Technology
Course: Metallic materials
Keywords: Strong magnetic field Solute drag effect Degradation of ferritic Carbide precipitation Degenerate pearlite Harbour temperature
CLC: TG142.15
Type: Master's thesis
Year: 2008
Downloads: 101
Quote: 1
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Abstract


Modern materials for steel industry increasingly stringent requirements, how to use more efficient and more environmentally friendly way to get integrated high-performance steel materials as researchers strive for the goal. Micro-alloying elements added to improve the alloy composition and sound processing and heat treatment process is one of the main two ways. The use of a strong magnetic field to heat treatment of the material is in this context to develop. Along with the development of a strong magnetic field generation technique, magnetic technology has been continually deepen and expand. Magnetic field as a new means of heat treatment is bound to iron and steel materials research and development of new materials have significant influence, but also on the continuous development of the field of materials science make a great contribution. In this paper, 12T isothermal heat treatment applied when a strong magnetic field at different temperatures at different times of isothermal method using optical microscopy, scanning electron microscopy, transmission electron microscopy, hardness tester, and other means to systematically study the magnetic field on the Fe-0.28% C- 3.0% Mo alloy ferrite transformation, carbide precipitation, pearlite transformation effects and from the transformation of both thermodynamic and kinetic analysis of the reasons for this effect produced, reached the following main conclusions. (1) In the Fe-0.28% C-3.0% Mo alloy, the temperature near the harbor and below by a degenerate ferrite, ferrite generating such mechanism is the solute drag effect and stimulate nucleation. Accelerated degradation of magnetic ferrite transformation kinetics, increased degradation ferrite transformation temperature of TTT curve harbor. No magnetic field when Fe-0.28% C-3.0% Mo alloy temperature at about 610 ℃ harbor around the outer harbor to strengthen the magnetic field around the temperature at 640 ℃. This is mainly due to the strong magnetic field reduces the solid phase free energy, reduce degradation of the barrier ferrite core, to reduce solute drag effect results. X-ray diffraction, high-resolution and energy spectrum analysis method to identify the types of carbide, carbide discover whether magnetic fields are the following three: (Fe, Mo) 2C, (Fe, Mo) 3C, (Fe, Mo) 6C; another, one carbide carbide can be converted into another. Strong magnetic fields than a single type of carbide precipitation. Strong magnetic field to promote the precipitation of carbides. Because different magnetization different carbide, a strong magnetic field is not the same as reducing the free energy, resulting in a strong magnetic field of carbide precipitation sequence changed. When the magnetic field were tested without degradation of pearlite forms. Strong magnetic field on the salient features of the pearlite transformation is the magnetic field narrowing pearlite lamellar spacing. The calculated results show that the magnetic field increases the pearlite transformation temperature. Theoretically well analyzed and explained the strong magnetic field on the pearlite transformation produces these effects causes.

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CLC: > Industrial Technology > Metallurgy and Metal Craft > Metallurgy and Heat Treatment > Metallic materials > Steel > Microstructure and properties of steel > Analysis of the steel test
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